1  private void HideForm()
 2         {
 3             string handlestr = System.Diagnostics.Process.GetCurrentProcess().MainWindowHandle.ToInt32().ToString();
 4             string path = Application.StartupPath + "\\Handle";
 5             if (!File.Exists(path))
 6             {
 7                 File.Create(path).Close();
 8             }
 9             using (StreamWriter writer = new StreamWriter(path, false))
10             {
11                 writer.Write(handlestr);
12             }
13             this.Hide();
14         }

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Windows.Forms;
 5 using System.Diagnostics;
 6 using System.Runtime.InteropServices;
 7 using System.IO;
 8 
 9 namespace NIKE.Client
10 {
11     static class Program
12     {
13         /// <summary>
14         /// 应用程序的主入口点。
15         /// </summary>
16         [STAThread]
17         static void Main()
18         {
19             //StaticPass.cf = new ClientForm();
20             //Application.EnableVisualStyles();
21             //Application.SetCompatibleTextRenderingDefault(false);
22             //Application.Run(new FormMain());
23             bool ret;
24             System.Threading.Mutex mutex = new System.Threading.Mutex(true, Application.ProductName, out ret);
25             if (ret)
26             {
27                 System.Windows.Forms.Application.EnableVisualStyles();   //这两行实现   XP   可视风格   
28                 //System.Windows.Forms.Application.DoEvents();             //这两行实现   XP   可视风格   
29                 Application.SetCompatibleTextRenderingDefault(false);
30                 System.Windows.Forms.Application.Run(new FormMain());
31                 //   Main   为你程序的主窗体，如果是控制台程序不用这句   
32                 mutex.ReleaseMutex();
33             }
34             else
35             {
36 
37                 string path = Application.StartupPath + "\\Handle";
38                 int handle = 0;
39                 using (StreamReader reader = new StreamReader(path))
40                 {
41                     handle = int.Parse(reader.ReadToEnd());
42                 }
43                 IntPtr i = new IntPtr(handle);
44                 bool isok = ShowWindow(i, 1);
45                 SetForegroundWindow(i);
46                 //  SetForegroundWindow(hWnd);
47                 // MessageBox.Show(null, "有一个和本程序相同的应用程序已经在运行，请不要同时运行多个本程序。\n\n本次打开无效", Application.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Warning);
48                 //   提示信息，可以删除。   
49                 Application.Exit();//退出程序   
50             }
51         }
52 
53         [DllImport("user32.dll")]
54         private static extern bool SetForegroundWindow(IntPtr hWnd);
55         [DllImport("user32.dll")]
56         private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);      
57         private const int SW_SHOWNORMAL = 1;
58        
59     }
60 }